The present invention generally relates to optical storage of information, and more particularly to an optical disk apparatus that uses a flexible and removable recording medium for recording information.
In the information storage devices for storing information, there has been a continuous demand for reducing the size of the device. In addition, there is a persisting demand for an increased storage capacity of information in any types of optical storage devices.
Conventionally, various storage devices are proposed and used for storing information. For example, use of a semiconductor memory device configured such as a so-called IC card device is proposed. In the IC card devices, one can form the device with a very small size particularly with respect to the thickness. However, the IC card devices generally has a drawback of small storage capacity of information. As the means for storing information, floppy disk devices are used also commonly. Particularly, compact floppy disk devices of the 3.5 inch size are used commonly. However, the device is still bulky and provides only a limited storage capacity.
Under such a situation, there is a proposal to construct an optical disk device that is capable of replacing the recording medium. According to the optical disk device of such a construction, a large storage capacity is guaranteed as a result of use of the optical recording and reproducing technique.
For example, Japanese Laid-Open Patent Publication 63-20732 describes a compact optical disk device that uses a detachable rotary optical recording disk and an optical head held on a swing arm, wherein the swing arm swings about an axis such that the optical head held at a tip end of the swing arm scans the recording surface of the rotary optical disk with the swinging motion of the arm.
More specifically, the swing arm provides a hollow passage of optical beam, and the optical head provided at the tip end of the arm includes a mirror for deflecting the optical beam in the direction perpendicular to the recording surface of the optical beam and a lens for focusing the optical beam thus deflected on the recording surface of the optical beam. In addition, there is provided an optical device in the swing arm in correspondence to the swing axis of the arm.
In order to accommodate the optical device in alignment with the axis of the swinging motion, the arm is held rotatably to the base of the optical disk device by upper and lower shafts separated from each other by a gap, and the detection device is accommodated into a space that is formed in correspondence to such a gap. In other words, the swing arm accommodates therein the optical device at the end that is opposite to the end at which the optical head is provided.
According to the construction of the device of the reference, one can record and reproduce information signals on and from the rotary optical recording medium by means of the optical head while swinging the arm about the axis.
On the other hand, the device has a problem, associated with the feature of providing the optical device at the space formed in correspondence to the gap between the upper and lower shafts, that a substantial part of the arm as well as a substantial part of the electromagnetic driving mechanism are located under the region that is covered by the optical disk when viewed in the direction perpendicular to the optical disk. Thereby, because of the thickness of the axial part of the arm as well as the thickness of the electromagnetic driving mechanism, the optical disk has to be mounted at a level above these bulky portions of the arm and the electromagnetic driving mechanism. Thereby, the device of the reference inevitably becomes thick and bulky, contrary to the requirement to reduce the size of the device.
Further, the device of the reference has a problem, associated with the fact that the arm is formed to be elastic for effecting the focusing control and the fact the mirror for deflecting the optical beam is fixed on the elastic arm, in that the focusing adjustment of the lens tends to invite various aberrations and decrease of luminosity due to the deviation of the optical path.